Sulfonic acid group-containing, proton-conducting polymer composition, a solid electrolyte membrane and a solid polymer fuel cell

Abstract

A solid electrolyte membrane for solid polymer fuel cells, or the like is provided that is chemically stable in a strong acid atmosphere, and has low methanol cross-over as well as high proton conductivity. The solid electrolyte membrane is manufactured, using an electrolyte composition comprising a sulfonic acid group-containing polymer having a specific triazine structure. This polymer can be synthesized, for example, from a sulfonic acid group-containing dihydroxy compound having a triazine structure, and a difluoride.

1. An electrolyte composition comprising a sulfonic acid group-containing polymer having at least one structure unit selected from the group consisting of a structure unit represented by formula (1), a structure unit represented by formula (2), a structure unit represented by formula (3), and a structure unit represented by formula (4), 
       
         
           
           
               
               
           
         
       
       (in formulae (1)-(4), Y is, independently for each formula, O, S or a direct bond; R is, independently for each formula, a group having at least either one of an unsaturated bond and an epoxy bond; Ar 1  is, independently for each formula, a sulfonic acid group-containing monovalent aromatic ring that may comprise fluorine or a fluorine-containing substituent group; Ar 2  is, independently for each formula and from each other in each formula, a divalent aromatic ring that may comprise fluorine or a fluorine-containing substituent group; A 3  is, independently for each formula, a divalent group comprising an aromatic ring that may comprise fluorine or a fluorine-containing substituent group; Ar 4  is, independently for each formula, a divalent group comprising a sulfonic acid group-containing aromatic ring that may comprise fluorine or a fluorine-containing substituent group; and Ar 5  is a phenylene group that may have 1 to 4 fluorine atoms as substituents). 
     
     
       2. An electrolyte composition according to  claim 1 , wherein said sulfonic acid group-containing polymer is cross-linkable by an active energy ray irradiation treatment, a heat treatment, or a combination thereof. 
     
     
       3. An electrolyte composition according to  claim 1  ,wherein said sulfonic acid group-containing polymer is a homopolymer, a random copolymer, a block copolymer, or a mixture thereof. 
     
     
       4. An electrolyte composition according to  claim 1 , wherein Ar 1  is, independently for each formula, a sulfonic acid group-containing phenyl group that may comprise fluorine or a fluorine-containing substituent group. 
     
     
       5. An electrolyte composition according to  claim 1 , wherein the two A 2 's in each formula are phenylene groups that may comprise fluorine or a fluorine-containing substituent group. 
     
     
       6. An electrolyte composition according to  claim 1 , wherein Ar 1  comprises one or two sulfonic acid groups. 
     
     
       7. An electrolyte composition according to  claim 1 , wherein Y is a direct bond, and R is a group selected from the group consisting of CH=CH 2 ,CH 2 CH=CH 2  and CF=CF 2 . 
     
     
       8. An electrolyte composition according to  claim 1 , wherein at least either one of Ar 3  and Ar 4  has a structure unit selected from the group consisting of a phenylene sulfone structure unit, a phenylene sulfoxide structure unit, a phenylene ketone structure unit, a phenylene ether structure unit, a benzoxazole structure unit, a benzothiazole structure unit and a triphenyl phosphine oxide structure unit. 
     
     
       9. An electrolyte composition according to  claim 1 , wherein the structure unit represented by formula (1) is obtained by reacting a compound represented by formula (5) and a compound represented by formula (6), 
       
         
           
           
               
               
           
         
       
       (in formulae (5) and (6), X 1  is, independently from each other, a group represented by formula (9) or (10); in formula (10), R 1  is, independently from each other, an alkyl group that may be branched; the other symbols have the same meanings as in formulae (1) to (4); and the sulfonic acid group in Ar 1  may be a salt of an alkali metal or an alkaline earth metal). 
     
     
       10. An electrolyte composition according to  claim 1 , wherein the structure unit represented by formula (2) is obtained by reacting a compound represented by formula (5) and a compound represented by formula (7), 
       
         
           
           
               
               
           
         
       
       (in formulae (5) and (7), X 1  is, independently from each other, a group represented by formula (9) or (in (10); in formula (10), R 1  is, independently from each other, an alkyl group that may be branched; the other symbols have the same meanings as in formulae (1) to (4); and the sulfonic acid group in Ar 1  and Ar 4  may be a salt of an alkali metal or an alkaline earth metal). 
     
     
       11. An electrolyte composition according to  claim 1 , wherein the structure unit represented by formula (3) is obtained by reacting a compound represented by formula (8) and a compound represented by formula (6), 
       
         
           
           
               
               
           
         
       
       (in formulae (8) and (6), X 2  is, independently from each other, a group represented by formula (9) or (10); in formula (10), R 1  is, independently from each other, an alkyl group that may be branched; and the other symbols have the same meanings as in formulae (1) to (4)). 
     
     
       12. An electrolyte composition according to  claim 1 , wherein the structure unit represented by formula (4) is obtained by reacting a compound represented by formula (8) and a compound represented by formula (7), 
       
         
           
           
               
               
           
         
       
       (in formulae (8) and (7), X 2  is, independently from each other, a group represented by formula (9) or (10); in formula (10), R 1  is, independently from each other, an alkyl group that may be branched; the other symbols have the same meanings as in formulae (1) to (4); and the sulfonic acid group in Ar 4  may be a salt of an alkali metal or an alkaline earth metal). 
     
     
       13. An electrolyte composition according to  claim 1 , wherein said sulfonic acid group-containing polymer has a number-average molecular weight (Mn) of 5,000 to 10,000,000. 
     
     
       14. An electrolyte composition obtained by subjecting the electrolyte composition according to  claim 1 , to an active energy ray irradiation treatment, a heat treatment, or a combination thereof. 
     
     
       15. A solid electrolyte membrane comprising an electrolyte composition according to  claim 1 . 
     
     
       16. A solid electrolyte membrane comprising an electrolyte composition according to  claim 14 . 
     
     
       17. A solid electrolyte membrane obtained by subjecting the electrolyte composition according to  claim 1 , to an active energy ray irradiation treatment, a heat treatment, or a combination thereof. 
     
     
       18. A solid polymer fuel cell using a solid electrolyte membrane according to  claim 15 . 
     
     
       19. A solid polymer fuel cell using a solid electrolyte membrane according to  claim 16 . 
     
     
       20. A solid polymer fuel cell using a solid electrolyte membrane according to  claim 17 . 
     
     
       21. A method for manufacturing a solid electrolyte membrane, wherein the electrolyte composition according to  claim 1 , comprises an organic solvent, said electrolyte composition comprising the organic solvent is applied to a substrate, and said solvent is removed thereafter. 
     
     
       22. A method for manufacturing a solid electrolyte membrane according to  claim 21 , wherein
 after the removal of said organic solvent, an active energy ray irradiation treatment, a heat treatment, or a combination thereof, is performed. 
 
     
     
       23. A method for manufacturing a solid electrolyte membrane according to  claim 21 , wherein
 a hot rolling treatment is performed after the removal of said organic solvent. 
 
     
     
       24. A method for manufacturing a solid electrolyte membrane according to  claim 22 , wherein
 a hot rolling treatment is performed after the active energy ray irradiation treatment, a heat treatment, or a combination thereof. 
 
     
     
       25. A solid polymer fuel cell using a solid electrolyte membrane manufactured by the method according to  claim 21 . 
     
     
       26. A solid polymer fuel cell using a solid electrolyte membrane manufactured by the method according to one of  claims 22  to  24 .